Steven Sinofsky, the executive who leads the Windows division, said that the biggest of the updates -- a massive 170MB download for Windows 8 x64 -- targeted performance, power management, media playback and compatibility issues which company developers uncovered and/or addressed since early August, when Microsoft tagged Windows 8 with the RTM, or "release to manufacturing," label.

In Microsoft's terminology, RTM designates the point at which it considers the code completed, and ready to ship to computer makers for installing on new PCs.

Microsoft has never updated a version of Windows between RTM and when the OS hits retail and PCs powered by it reach stores.

"Very interesting," said Jason Miller, manager of research and development at VMware, and a frequently-cited source on patching. "We've never seen them do something like this before. They're definitely changing how they do things to add more features on the fly."

Others also applauded. Andrew Storms, director of security operations at nCircle Security, called it a "welcome change" and added, "End users should be happy knowing they are going to get the latest advancements in their Windows 8 install."

Typically, Microsoft has reserved most major changes for what it calls "Service Packs," collections of previously-released security patches, non-security bug fixes, and new features or improvements of existing ones. Service packs are usually issued every 18 months or so; Windows 7, for example, has seen only one such upgrade in the three years since its Oct. 2009 launch, Service Pack 1 (SP1), which shipped in Feb. 2011.

"There are always things you were aware of as you develop that you deferred fixing, because if you didn't you'd never finish the software," said Michael Cherry, an analyst with Directions on Microsoft and former Microsoft program manager. "Because there was no mechanism for releasing them as they were finished, you had to wait for a service pack."

Sinofsky described how in the past, Microsoft would make scores of changes to accommodate new PCs that computer makers had created, but that previously it had no way to distribute the resulting improvements to all users, including those running the new OS on older systems.

"During the final months of Windows 8 we challenged ourselves to create the tools and processes to be able to deliver these 'post-RTM' updates sooner than a service pack," Sinofsky wrote. "By developing better test automation and test coverage tools ... Windows 8 will be totally up to date for all customers starting at General Availability."

General Availability, or GA, is Microsoft-speak for the official launch and on-sale date.

Analysts and experts searched for reasons why Microsoft broke with tradition to push what wags have already pegged as "Service Pack 0.1."

"What's the mindset that they really want to break?" Cherry asked. "They want consumers and enterprises to believe that they don't have to wait for a service pack [to install Windows 8]. This is more of a statement of direction than anything. Microsoft's saying, 'We can get stuff to you on the fly, so as we discover, validate, fix and test, we now have a mechanism to release them.'"

A long-held rule-of-thumb, especially among IT administrators, was that it was smart to wait until bugs had been rooted out -- and a first service pack released -- before deploying a new edition of Windows. But that rule has been relaxed in the last few years, as Microsoft has encouraged users to begin upgrades before SP1. In 2007, for example, Microsoft argued that service packs were no longer necessary, then hemmed and hawed for months before finally announcing SP1 for Vista.

More recently, Microsoft touted regular updates as a reason why customers should acquire the upcoming Office 2013 by subscribing to one of its Office 365 plans.

"This 'slipstreaming' of updates is really not any different than what Apple has been doing for a long time," said Cherry. "They release iOS but then updates come pretty quickly."

Miller echoed that. "Look at Google, they're constantly introducing new features in Chrome OS," Miller said. "Browsers on Windows are the same. Google and Mozilla are constantly updating [Chrome and Firefox]. So Microsoft is just getting into what other vendors are doing, adding minor functionality. It may get people a little more excited about Windows 8."

"I see them driven by the Surface PCs, which are sealed units," said Cherry of Microsoft-made hardware. The first Surface, a tablet powered by Windows RT, was unveiled in June and will go on sale in two weeks. "They're totally reliant on over-the-network updates. Some won't have DVD drives -- optical drives are likely to go away -- and as these sealed devices get more popular, on-the-fly updating is the way to go."

Apple has already ditched optical drives from its notebook lines, and those machines as well as the iPad, are usually updated over-the-air via wireless networks. The Cupertino, Calif. company has never collected updates into service pack-style bundles, but has instead issued multiple updates to OS X over the course of each year.

Sinofsky did not explicitly declare service packs dead, but he seemed to hint it was on the cusp of obsolescence, and that Microsoft plans to deliver not only fixes and patches, but also new and improved features, via Windows Update.

"We think this new pace of delivering high-quality updates to Windows will be a welcome enhancement for all of our customers," said Sinofsky Tuesday.

There are risks to Microsoft's strategy, warned Miller and Storms. While enterprises traditionally test service packs before they're deployed throughout an organization, the security experts wondered if that would still take place when Microsoft instead delivers a larger number of smaller updates that may include new tools and features, or even "Modern"-style apps.

"My concern is that users may blindly put things on their systems," said Miller. "It's going to challenge organizations to expand their maintenance and testing Windows. We're going to have to adapt."

"Windows Update is an established and trusted delivery mechanism. but if a user installs an update from Windows Update and experiences a blue screen, then that trust will be lost," said Storms.

Even Cherry chimed in. "Back when Patch Tuesday got started, it didn't have a good track record and so a lot of us were concerned about mixing bug fixes and features together. Now, its track record is much better. But you're only as good as your last update."

Some Windows 8 users were thinking more about the size of Tuesday's update than about any potential problems in the future.
"Wow, I don't remember the last time I've downloaded a 170MB patch from Windows Update that wasn't a Service Pack or a new app," said "Entegy" in a comment on Sinofsky's blog.

"Holy crap, this Windows 8 update today is 170MB. I think it's awesome they are doing this but I feel like an iTunes user," said blogger Robert McLaws on Twitter Tuesday, making fun of Apple's notoriously-huge updates for the music software and App Store.